1. Field of the Invention
The present invention relates to an actuated wedge socket assembly for termination of a wire rope. In particular, the present invention relates to an actuated wedge socket assembly which provides controlled loading which will enhance efficiencies of the wire rope and wedge socket assembly.
2. Prior Art
Wire rope or wire line is often used to lift, pull or move heavy objects. One type of wire rope consists of several strands which are laid or twisted together in a helical pattern. Each strand may likewise be made up of metal wires twisted or laid together in a helical pattern. Wire rope is frequently made from carbon steel wires, although other materials may be used as well.
Wire rope can be used to transmit motion through various planes or angles, can be used to tie down or hold back objects, and can be used to counter balance, guide or lift objects.
The end of a wire rope can not be easily connected to objects or equipment and, accordingly, there are different ways to secure the ends of a wire rope. Ideally, force and motion are transferred from the end of the wire rope efficiently. End terminations are, therefore, of great importance for transferring these forces and motions.
Examples of wire rope terminations include wire rope sockets (open and closed spelter and swage), mechanical splice terminations, and clip terminations. Another type of wire rope termination which may be installed in the field is a wedge socket, which is simple, easy and quick to apply and to disassemble.
A wedge socket termination is useful in a number of applications. One application would be in a high-wear region where the rope may be periodically trimmed, requiring the termination to be removed and reapplied.
In order to attach a wire rope to a wedge socket, one end of the wire rope is passed through a hollow basket or socket from a smaller opening to a larger opening. Thereafter, the wire rope is positioned in a peripheral groove around the circumference of a wedge. The end of the wire rope is then run back through the hollow basket of the wedge socket from the larger opening to the smaller opening. The wedge with the wire rope around the circumference is then inserted into the open basket of the wedge socket, trapping the wire rope between the edge of the wedge and the interior of the basket. The taper of the wedge and the taper of the inside of the basket or socket combine so that when tension is put on the wire rope, the wedge is pulled by the wire rope and firmly held in place.
An example of an existing wedge socket design is disclosed in Assignee's U.S. Pat. No. 4,845,814 entitled “Wedge Socket”. In addition, Assignee's U.S. Pat. No. 5,953,360 entitled “Extended Wedge Socket Assembly” discloses a wedge socket assembly having an extended portion on the smaller end of the wedge to act as a retaining mechanism for retaining the wedge in the socket.
During the process of seating the wire rope and the wedge in the socket, the wire rope will be formed and/or compressed. Because of this, end terminations will not develop the full strength of the wire rope used. The wire rope industry has determined terminal efficiencies for various types of end terminations. The efficiency of a termination is a rating derived as a ratio of the expected ultimate strength of the terminated wire rope assembly to its published catalog breaking strength. Wedge sockets should achieve an efficiency of approximately 70 to 80%. The efficiency is defined as a percentage of the load carrying force of the wire rope within the wedge socket assembly after installation. For example, for a 50,000 pound breaking strength wire rope, an 80% efficiency would mean that the wire rope within the assembled wedge socket would support up to 40,000 pounds of force. For example, the U.S. Federal government has a specification that wire rope sockets should have an ultimate assembly strength of about 70% of the wire rope strength (see Federal Specification RRS550D entitled “Sockets, Wire Rope”).
As the diameter of the wire rope increases, so does the difficulty in manually manipulating the wire rope around the wedge and into the socket. Accordingly, it would be desirable to have an actuated wedge assembly to assemble the termination in the field.
Additionally, recently, new high strength wire rope designs have been developed which include compacted strand and rotation resistant ropes. These new high strength wire ropes are often compacted, swaged or formed during manufacture in order to minimize the diameter and maximize the metal cross section. These high strength wire ropes tend to be stiffer and more resistant to bending than traditional wire ropes and, accordingly, have greater difficulty accommodating the relatively sharp bending radius during assembly when the wire rope is wrapped around the peripheral edge of the wedge.
The standard procedure to assemble a wire rope wedge socket assembly in the field is for an installer to drive the large end of the wedge and the wire rope into the wedge socket as deep as possible with a hammer (see Wire Rope Technical Board—Wire Rope Users Manual). The force from hammering is not measured and may vary widely. Thereafter, the installer is instructed to apply a first or test load to the live end of the wire rope to fully seat the wedge into the socket. A slight tilting of the wedge within the socket may occur due to an unbalanced load being applied to the wedge during the recommended first load to fully seat the wedge application. The unbalanced load occurs because only the live line is acting to seat the wedge, and the tendency is for the wedge to rotate due to the moment being applied.
Through testing, Applicants have determined that the assembly pre-load requirements vary depending on the unique construction and manufacturing processes of different brands of wire rope. The traditional methods of hammering the wedge into place and applying a random first load may not achieve the desired wire rope termination efficiency.
Accordingly, it is desirable to provide an actuated mechanism as a method to engage and assemble a wedge and wire rope with a wedge socket.
It is an additional object and purpose of the present invention to provide controlled seating of the wire rope and the wedge in the wedge socket at the time of assembly.
It is a further object and purpose of the present invention to assist in the installation of a wedge and wire rope into a wedge socket.
It is a further object and purpose of the present invention to provide increased efficiency of wedge socket terminations with use of an external force to seat the wedge and wire rope in the socket.
It is a further object and purpose of the present invention to provide increased efficiency of wedge socket terminations by uniformly and evenly loading the wedge and rope into the wedge socket.
It is a further object and purpose of the present invention to provide a mechanical mechanism to seat the wedge and wire rope in the socket using tools readily available in the field.
It is a further object and purpose of the present invention to provide an actuated wedge socket assembly that may be utilized for new applications and may also be retrofit to existing wedge socket assemblies.